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   <div id="projectname">lwIP
   &#160;<span id="projectnumber">2.1.2</span>
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<a href="#define-members">Macros</a>  </div>
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<div class="title">Loopback interface<div class="ingroups"><a class="el" href="group__lwip.html">lwIP</a> &raquo; <a class="el" href="group__lwip__opts.html">Options (lwipopts.h)</a> &raquo; <a class="el" href="group__lwip__opts__netif.html">NETIF</a></div></div>  </div>
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Macros</h2></td></tr>
<tr class="memitem:gaa2b1f736373cd896e212644aa453fbaf"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__lwip__opts__loop.html#gaa2b1f736373cd896e212644aa453fbaf">LWIP_HAVE_LOOPIF</a>&#160;&#160;&#160;(<a class="el" href="group__lwip__opts__loop.html#ga724a0ea765d5a47d026d529725f31c01">LWIP_NETIF_LOOPBACK</a> &amp;&amp; !<a class="el" href="group__lwip__opts__netif.html#ga943063b053eeac76b0b1bcef2ddd93be">LWIP_SINGLE_NETIF</a>)</td></tr>
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<tr class="memitem:ga10a878b390c2fbe421d82502001c7300"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__lwip__opts__loop.html#ga10a878b390c2fbe421d82502001c7300">LWIP_LOOPIF_MULTICAST</a>&#160;&#160;&#160;0</td></tr>
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<tr class="memitem:ga724a0ea765d5a47d026d529725f31c01"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__lwip__opts__loop.html#ga724a0ea765d5a47d026d529725f31c01">LWIP_NETIF_LOOPBACK</a>&#160;&#160;&#160;0</td></tr>
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<tr class="memitem:gaacc3ad5d0a771d45fb0a3e3a09b1dbea"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__lwip__opts__loop.html#gaacc3ad5d0a771d45fb0a3e3a09b1dbea">LWIP_LOOPBACK_MAX_PBUFS</a>&#160;&#160;&#160;0</td></tr>
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<tr class="memitem:gaa28d13ddd5281b1912276991e7ea58c5"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__lwip__opts__loop.html#gaa28d13ddd5281b1912276991e7ea58c5">LWIP_NETIF_LOOPBACK_MULTITHREADING</a>&#160;&#160;&#160;(!<a class="el" href="group__lwip__opts__nosys.html#gae00ba99de94a5bf84d832be8976df59b">NO_SYS</a>)</td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<h2 class="groupheader">Macro Definition Documentation</h2>
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<h2 class="memtitle"><span class="permalink"><a href="#gaa2b1f736373cd896e212644aa453fbaf">&#9670;&nbsp;</a></span>LWIP_HAVE_LOOPIF</h2>

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          <td class="memname">#define LWIP_HAVE_LOOPIF&#160;&#160;&#160;(<a class="el" href="group__lwip__opts__loop.html#ga724a0ea765d5a47d026d529725f31c01">LWIP_NETIF_LOOPBACK</a> &amp;&amp; !<a class="el" href="group__lwip__opts__netif.html#ga943063b053eeac76b0b1bcef2ddd93be">LWIP_SINGLE_NETIF</a>)</td>
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<p>LWIP_HAVE_LOOPIF==1: Support loop interface (127.0.0.1). This is only needed when no real netifs are available. If at least one other netif is available, loopback traffic uses this netif. </p>

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<h2 class="memtitle"><span class="permalink"><a href="#gaacc3ad5d0a771d45fb0a3e3a09b1dbea">&#9670;&nbsp;</a></span>LWIP_LOOPBACK_MAX_PBUFS</h2>

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          <td class="memname">#define LWIP_LOOPBACK_MAX_PBUFS&#160;&#160;&#160;0</td>
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<p>LWIP_LOOPBACK_MAX_PBUFS: Maximum number of pbufs on queue for loopback sending for each netif (0 = disabled) </p>

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<h2 class="memtitle"><span class="permalink"><a href="#ga10a878b390c2fbe421d82502001c7300">&#9670;&nbsp;</a></span>LWIP_LOOPIF_MULTICAST</h2>

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          <td class="memname">#define LWIP_LOOPIF_MULTICAST&#160;&#160;&#160;0</td>
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<p>LWIP_LOOPIF_MULTICAST==1: Support multicast/IGMP on loop interface (127.0.0.1). </p>

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<h2 class="memtitle"><span class="permalink"><a href="#ga724a0ea765d5a47d026d529725f31c01">&#9670;&nbsp;</a></span>LWIP_NETIF_LOOPBACK</h2>

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          <td class="memname">#define LWIP_NETIF_LOOPBACK&#160;&#160;&#160;0</td>
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<p>LWIP_NETIF_LOOPBACK==1: Support sending packets with a destination IP address equal to the netif IP address, looping them back up the stack. </p>

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<h2 class="memtitle"><span class="permalink"><a href="#gaa28d13ddd5281b1912276991e7ea58c5">&#9670;&nbsp;</a></span>LWIP_NETIF_LOOPBACK_MULTITHREADING</h2>

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          <td class="memname">#define LWIP_NETIF_LOOPBACK_MULTITHREADING&#160;&#160;&#160;(!<a class="el" href="group__lwip__opts__nosys.html#gae00ba99de94a5bf84d832be8976df59b">NO_SYS</a>)</td>
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<p>LWIP_NETIF_LOOPBACK_MULTITHREADING: Indicates whether threading is enabled in the system, as netifs must change how they behave depending on this setting for the LWIP_NETIF_LOOPBACK option to work. Setting this is needed to avoid reentering non-reentrant functions like <a class="el" href="tcp__in_8c.html#ae70c3c99d9dd6b07f7e11f7ba5eedcb5">tcp_input()</a>. LWIP_NETIF_LOOPBACK_MULTITHREADING==1: Indicates that the user is using a multithreaded environment like <a class="el" href="tcpip_8c.html">tcpip.c</a>. In this case, netif-&gt;input() is called directly. LWIP_NETIF_LOOPBACK_MULTITHREADING==0: Indicates a polling (or NO_SYS) setup. The packets are put on a list and <a class="el" href="netif_8c.html#a0fbaed78253d21e1b54e65651da3e327">netif_poll()</a> must be called in the main application loop. </p>

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